1. Field of the Invention
The present invention relates to a channel equalization and decoding device for frequency selective channels.
2. Description of Related Art
In digital transmission, the solutions proposed generally use channel equalization and coding processes. In the conventional approach, the elementary channel equalization and coding functions are processed separately, utilizing only part of the information placed at their disposal. Therefore, the overall performance of the receiver remains suboptimal.
An aim of the invention is to remedy this drawback.
For a few years now, several authors prompted by the techniques of turbo-codes [1] have proposed solutions based on a maximum likelihood detector, an interference canceller and channel coding to combat interference between symbols. Among these solutions let us briefly recall the most significant contributions.
In 1995, a receiver called a turbo-detector [2] associated a detector based on maximum a posteriori likelihood with a channel decoder, through an iterative procedure. The performance obtained was then quasi-optimal for many channels. However, the turbo-detector remained reserved rather for modulations with a small number of states and for channels having short impulse responses.
In 1997, another turbo-equalizer receiver [3] was devised with the aim of being able to reduce the complexity of the turbo-detector and of being able to quasi-optimally equalize modulations with a large number of states on channels exhibiting considerable spreading with respect to the symbol duration.
An aim of the invention is to improve the performance of both of the aforementioned receivers.